Speaking up for those who can't speak

So recently I got kicked out of a group on Facebook for "bullying". This is the absolute first time I have ever been called a bully in my life, and while I greatly disagree that what I did was bullying, if it was then I think I just found the only situation in the world where it's ok to "bully". Here's what happened. I never find myself involved in Facebook drama because I really only use the site to look at pictures of friends and family who live far away, and keep in touch with invites for birthday parties, baby showers etc. I've never been involved in an argument on Facebook. I don't feel it's the place. Well I joined a group on there for people to buy/sell/trade things in my area. It clearly states in the rules of the group that it is not to be used to buy or sell animals. Some people dont follow that rule and it always bugs me because animals aren't like a piece of furniture you buy new and then sell when you're bored with it. They are a living thing, that grows to love, trust, and depend on you. You don't go selling it the first person who offers you $50 on Facebook! So today when somebody was trying TRADE a dog they FOUND for an iPhone, I finally said something. I don't think I was rude or mean about it, though maybe it wasn't my place. My exact words were: "a dog is not a token to be traded. Somebody is probably missing their best friend dearly and you should be contacting the local animal shelters instead of trying to pawn it off on somebody who may or may not care for it correctly, so that you can get a new phone." And then I tagged the local animal shelters' Facebook pages. I then received a message from the admins of the group saying I wasn't allowed to post there anymore. That's fine with me. I don't feel I did anything wrong, and hopefully the shelters will see and contact the dogs owners. I hope somebody would Do that for me if it were my dog. do any of you ever feel compelled to help animals in this way? Feel like they are so beautiful and yet so helpless that we must step in, to ensure their giving and loving hearts aren't taken advantage of?
updated by @emmy-long: 09/02/18 02:05:46PM

I think you did the right thing. People have no right to use animals like that. I always get angry when people think hat they own the earth or something and can trade animals as they wish. Animals are not a commodity and they have rights too. You certainly did the right thing!